Lithofacies and Geochemical Properties of Neogene Deposits at South of Tuzgölü-Turkey

Abstract

The Tuzgolu Basin located at the Central Anatolia (Turkey) is bounded by Ankara uplift at the north, the Kirsehir massif from at the east and the Sivrihisar-Bozdag massive at the west. In the study area which is located at the South of the Tuzgolu, the Paleogene and Mesozoic marine carbonates and igneous rocks underlies the Neogene sequences.Neogene deposits consist of Kizilbayir, Katrandedetepe and Bestepeler formations which are conformable with each other. 10 different lithofacies were identified within the Neogene sequence by considering sedimentation conditions, lithology, sedimentary structure and fossil content.; Grain-supported conglomerate facies (Gcu), Convolute bedded sandstone facies (Sk), Thick-bedded sandstone facies (St), Gray-purple colored thick layered mudstone facies(Mt), Oolitic limestone facies (OC), Alternating gypsum-anhydrite-mudstone-micritic limestone facies (Cmag), Bituminous shale facies (Bs), Halite-mudstone facies (Hm), Massive and parallel laminated tuff facies (Pmlt), Alternating mudstone-sandstone facies (Ms). The facies analysis show that sedimentation in the study area began with fluvial sediments (Kizilbayir formation) and followed by sediments of shallow lake which was often interrupted by sediments from land (Katrandedetepe formation) , and by the interbedded mudstone, sandstone, conglomerates and tuff at the closure of the lake (Bestepeler formation). According to the geochemical analysis results obtained from lake carbonate and evaporite deposits (Halite, anhydrite and gypsum), REE, LILE and HFSE values are more abundant in clayey samples than those in other evaporatic sediments. The Sr contents of halites (1-1539 ppm) are lower than sulfate (183-4378.04 ppm) and carbonates (922-12365 ppm). Halite minerals contain very high Cl (505686-615905 ppm) and low Br (5-637 ppm) indicating that they are products of dissolution, mixing and re-precipitation.